Al60Mn13Ti25V2 intermetallic was heat treated by two ways.One was complex treatment of hot isostatic pressing (HIP)at 1200℃ and 173 MPa for 4 hours following homogenization treatment in vacuum furnace (4×10-4Pa)at 1100℃ for 48 hours.The other way was just homogenization treatment with the samecondition.Static and cycle oxidation behavior of the alloys treated by the two ways were studied at 900℃ and 1000℃ respectively.The results showed that oxidation resistance was high for the both treated alloys under the condition of static oxidation.Under the condition of cycle oxidation,ho wever,the oxidation resistance of the HIP treated alloy was much better than that of the single homogenized treatment.The reason was that the HIP decreased porosity and Mn-rich region.

Intergranular corrosion and exfoliation of peak-aged AA2090 and AA8090 Al-Li alloys were studied.For peak-aged AA2090 alloy,due tonumerousT1 precipitations within grains and the selective dissolution of T1,the electrochemical dynamic of intergranular corrosion is determined.For peak-aged AA8090 alloy,because of selective dissolution of thick continuous T2 precipitates at grain boundary,severe intergranular corrosion occurs.Owing to the difference of microstructure and intergranular orrosion,AA8090 alloy is very susceptible to exfoliation corrosion,while only superficial exfoliation w ith tiny flakes appears in AA2090 alloy.

Double glow discharge is applied to pure copper substrate to obtaintitanizing alloying layer.The high temperature oxidation resistance of the plasma titanizing samples at 400℃ and 700℃ wasinvestigated.The oxidation kineticscurve was worked out.The morphologies of oxidation surface were observed and analyzed with a scanning electron microscope and the oxidation mechanism was ssed.The results show that plasma titanizing on copper surface can improve greatly the high temperatureoxidation resistance of copper.The oxidation rate of copper is less than that of plasma titanizing.The oxidation film of plasma titanizing sample is very dense and is not easily exfoliated.The dense oxidation film prevents the copper from more oxidation.

The microstructures of the crack induced by hydrogen and crack healing have been studied by using the transmission electron microscopy(TEM).These specimens of carbon steel with the hydrogeninduced cracks were cyclically annealed at 1000℃ for 10 h.The SEM and TEM observations on the specimens before and after the heat treatment showed that the cracks could be healed completely by heat treatment.The healing of hydrogeninduced cracks was closely related to heat diffusion of Fe and C atoms.The driving force of crack healing resulted from the plastic deformation energy Es created by the growth of hydrogen bubbles or cracks.The critical condition of healing of bubbles or cracks isEs≥2γ/r(whereγis the surface tension,r is the half length of crack).During healing of the hydrogeninduced cracks,the dislocation density around grain boundaries decreased and the dislocation type transformed from tangle dislocation with high energy to vertical and regular dislocation with low energy.The formation of pearlite in distinct layers during healing process indicated the structure of carbon steel recovered too.

The corrosion of 7 kinds of mild steel and low alloy steelin immersion-wet-dry cycle test environment and the electrochemical feature of rusted metals after test were studied by using EIS and SEM et al.The solution containing HSO-3 and Cl-,was used for wetting and immersion specimens at circumstance emperature 40℃ for 4 min respectively.The drying cycle was maintained for 12 min at temperature 12℃.The results indicated that,the weight loss all followed exponential decay function:Y=Y0+Ae-t/B.The corrosion rate of mild steel was 2.49 times than that of the most corrosion resistant low alloy after 120 h test.The results of electrochemical measurement showed that,the further corrosion rate would be controlled by cathodic diffusion process.The impedance of 7 kinds of steels after corrosion test was linear with the annual corrosion rate.

The corrosion of 7 kinds of mild steel and low alloy steel in immersion-wet-dry cycle test environment and the electrochemical feature of rusted metals after test were studied by using EIS and SEM et al.The solution containing HSO-3 and Cl-,was used for wetting and immersion specimens at circumstance temperature 40℃ for 4 min respectively.The drying cycle was maintained for 12 min at temperature 12℃.The results indicated that,the weight loss all followed exponential decay function:Y=Y0+Ae-t/B.The corrosion rate of mild steel was 2.49 times than that of the most corrosion resistant low alloy after 120 h test.The results of electrochemical measurement showed that,the further corrosion rate would be controlled by cathodic diffusion process.The impedance of 7 kinds of steels after corrosion test was linear with the annual corrosion rate.

The role of salt particle deposition in the initiation and propagation of atmospheric corrosion was studied using potential distribution measurement.The results showed that the necessary condition for the atmospheric corrosion initiation was the relative humidity higher than that over saturated solution of the salt particle,during which the salt particle absorbed water from the air and condensed rolyte layer on the metal surface.At the same time,non-homogeneous potential distribution with volcano type was formed around the place of salt deposition.The peak potential Ep and valley potential Ev changed drastically with rapid change of relative humidity,while the potential of the metal matrix remained.The difference of the peak potential and the valley potential Ep-Ev,the potential difference of the corrosion battery,increased rapidly with increasing the number of dry-wet cycles,which increased corrosion rate,too.It was also found out that the chemical distributions has close relationship with potential distribution on the metal surface with salt particle deposition.The model described the non-homogeneous potential distribution over the metal with salt deposition was proposed and the initiation and propagation of atmospheric corrosion caused by the salt deposition was elucidated,based on above findings.

A strain of Thiobacillus denitrificans was isolated from soil,which was selected to reduce the corrosion caused by SRB.The optimal pH was determined as 7.0 for the growth of T.denitrificans and the growth curve was measured.The growth environment of T.denitrificans was found to be similar to that of SRB.T.denitrificans and SRB could grow together in mixed medium.A laboratory investigation using scanning probe microscopy and electron probe microanalysis(EPMA)had been undertaken to study the compactness of biofilms,composed of corrosion products in mixed medium.It was observed that T.denitrificans could reduce the corrosion caused by SRB which attributed to that it could consume the corrosive sulfide produced by SRB and limit the sulfide accumulating in biofilms.So the content of sulfide in biofilms decreased and the extracellular polymeric substances of T.denitrificans enhanced the compactness of biofilm.Therefore,the process of charge transfer was baffled,leading to a decrease of the corrosion caused by SRB.

The crack propagation characteristics of X70 pipeline steel in the synthetic soil solution under cyclic loading are investigated.The macroscopical rules of the crack propagation are analyzed as well.Results indicate that the crack propagation is controlled mainly by the crack tip stress intensity factor range ΔK.The loading frequency (0.1 Hz～10 Hz) has little affect on the crack propagation rates in the synthetic high pH soil solution (pH=9.3).The crack propagation rate increases with the decrease of loading frequency (0.1 Hz～10Hz) in the synthetic nearneutral soil solution.Considering the crack ing propagation characteristics,the crack propagation quantitative models of the loading frequencyf=0.1 Hz～10 Hz in the synthetic high pH soil solution and near neutral soil solution are put forward respectively.

Photo-oxidation initiated by ultraviolet ray (UV) is a pivotal factor which affects degradation of the coatings.Quartz crystal microbalance (QCM) testing results show that the absorbance of water and SO2 in the coatings increases remarkably after exposure to UV.Changes in porosity after exposure were means of electrochemical impedance spectroscopy (EIS),and the results show that the porosity increases with the increase of exposure time.Fourier transform infrared spectroscopy (FTIR) analysis shows that reakdowoccurs in the C-chain of the coatings after exposure to UV,which occurs at C-O bond of aromaticester for the alkyd resin and at C-O bond of aromatic ester and C-N bond of urethane for the olyurethane resin.Some hydrophilic groups may be formed simultaneously.Scanning electron microscope (SEM) was employed to analyze the morphology of the coatings and the results show that many pores and holes were formed after exposure to UV.It was suggested that the increase of water is the cooperation of the increases both of the amount of hydrophilic groups and of the porosity of the coatings,but the contribution of the increase of porosity may be greater.The increase of absorbance of SO2 is the cooperation of the increase ofα-H peroxide and the increase of porosity,but the contribution of theincrease of α-H peroxide may be higher.

The conventional weight-loss tests and the electrochemical techniques were used to study the inhibition action of four inhibitors for copper in boiling deaerated 60%LiBr solution.It indicated that the corrosion rate of copper was decreased when LiOH,Na2MoO4 or BTA was added to the solution either ndividual or in different combination.The inhibition effect of combination was better than that of ndividual for LiOH not only benefited forming passive film but also accelerated the reaction of CuBTA and reduction products such as MoO2 participated in forming passive film.The optimal proportioning was added 0.10 mol/L LiOH,150 mg/L Na2MoO4 and 100 mg/L BTA to LiBr solution and the corrosion rate of copper was decreased to 39.52 μm/a.LiNO3 had little effect in inhibiting the dissolution of copper for the following reasons.The diffusion velocity of NO-3 was slower than the others.NO-3enhanced the tend ency of pitting and its reducing reaction was restrained by LiOH.The order of inhibition effect was LiOH>BTA>Na2MoO4>LiNO3.

Effect of different laser powers on microstructures and wear properties of laser cladding WCP/Ni etal ceramics coating was studied in this paper.The WCP/Ni alloy coating with the even-distributed WC ceramics phases and the better bond with the substrate alloy was obtained by choosing 2.2 kW power.Diffusion reaction solution happened between the WC particles and the substrate alloy during laser cladding,giving rise to the formation of block rich-tungsten carbide on the edges of the WC particles,especially in higher power.The WCP/Ni alloy coating consisted of the undissolved WC particles,the block or dendritic rich-tungsten carbide,the bar-like rich-chromium carbide.and dendrit e solid solution and eutectic structure among them.Microhardness and wear resistance of the WCP/Ni coating in different powers were much higher or better than Ni60 alloy coating,and were best in 2.2 kW power.

This paper reviews some factors affecting the coking behaviors of metal materials,which are the temperature of the carbon-containing atmosphere, the kinds and the surface state of metal materials, and the kinds and ratio and flowing velocit of the gases forming the carbon-containing atmosphere,and then introduces the initiating mechanism of catalytic coking and its applications. Taking the Fe-Cr-Ni alloy as an example, the paper also respectively introduces two kinds of carburizing behaviors, i.e. inner carburizing and metal dusting , and then reviews the effects of temperature, carbon-containing atmosphere, as well as crystal structure and element constitution of the alloy on the inner carburizing and metal dusting . Finally the relations between coking and carburizing are analyzed, and three kinds of protective methods including adding coking inhibitor,adjusting structure and element constitution of metal materials, and preparing coating are introduced.